Amid the ongoing manhunt for the suspect who left his backpack, police said they were not ruling out any possibility including retaliation by Uighurs for sending them back to China. Thailand recently deported dozens of Uighurs to China sparking widespread criticism.

"Police are not ruling out anything including (Thai) politics and the conflict of ethnic Uighurs who, before this, Thailand sent back to China," National police chief Somyot Pumpanmuang said.

No group has claimed responsibility for the attack on the Hindu shrine, which is also popular among Buddhists. The recent deportation of 109 Uighur refugees by Thai authorities is seen as China's increasing pressure on Thailand to crack down on the ethnic community.

Police said it was unclear whether the suspect was a Thai national or of foreign origin. Multiple Thai news outlets including the Bangkok Post, citing police sources, reported that investigators were examining whether the incident had any connection to Uighur extremists.

"That man was carrying a backpack and walked past the scene at the time of the incident. But we need to look at the before and after CCTV footage to see if there is a link," Somyot told reporters.

Security experts have said the blast does not fit the pattern of operations carried out by known local groups in Thailand. The groups which primarily operate in Thailand are the loosely-organised Malay-Muslim separatist movement, the Barisan Nasional Revolusi (BRN), and the radical "Red Shirt" campaigners who are opposed to the military regime.

Though the Muslim separatists have been active in Thailand, such groups are largely confined to the southern region of the country - primarily three provinces, Pattani, Narathiwat and Yala. There are no previous records of them carrying out attacks in Bangkok.

When asked about the Uighur link to the bombing, Prime Minister Prayut Chan-o-cha however sidestepped the question at a press conference.

"Whether this incident was motivated by domestic politics or an international issue, I don't want to give you an opinion because it could mislead investigators and cause panic. This incident shows us our country still has a person or a group of people with hostility to the nation operating actively.

"They may be doing it for a political motive or to undermine the economy or tourism or for other reasons. The government will investigate and find the perpetrators and their accomplices as soon as possible."